The isokinetic rotator cuff strength ratios in overhead athletes: Assessment and exercise effect

Kinematic, electromyographic and isokinetic measurements for the management of shoulder subacromial pain syndrome: A systematic review

BACKGROUND

Subacromial shoulder pain syndrome is a very common and challenging musculoskeletal disorder. Kinematics, electromyographic muscle activity and isokinetic dynamometry are promising non-invasive movement analysis tools to improve understanding of this condition. No review has combined their results to provide a better understanding of the effects of subacromial pain syndrome on shoulder movement. This systematic review aimed to synthesise the associations between exposure to shoulder pain due to subacromial pain syndromes or subacromial impingement and changes in shoulder movement measures.

METHODS

The databases were Scholar google, Pubmed, Science Direct, Scopus and the Cochrane Library. We included studies that observed the association of the presence of subacromial pain syndromes or subacromial impingement with changes in shoulder motion measures.

FINDINGS

Seventeen studies with 943 participants were included. The main kinematic change was a lower scapular posterior during abduction in the subacromial pain syndrome group with a "low" level of evidence (standardised mean difference = -0.61, 95% confidence interval [-0.80; -0.43]). The main electromyographic change was an earlier onset of activation of the upper trapezius in the subacromial pain syndrome group, with a "moderate" level of evidence (standardised mean difference = 1.01, 95% confidence interval: [-2.97; 0.96]). The main isokinetic change was a lower peak internal rotator torque in the subacromial pain syndrome group, with a 'low' level of evidence (standardised mean difference = -0.41, 95% confidence interval: [-0.53; -0.29]).

INTERPRETATION

The variables measured during movement are associated with subacromial pain syndrome or subacromial impingement syndrome. Consistency between the results supports the importance of scapula biomechanics measurements in these conditions.

Return to Sports Following Shoulder Injury: Clinical Evaluation, Isokinetic, and Functional Testing

ABSTRACT

The shoulder is commonly injured in overhead sports. This is associated with a high degree of mobility at the expense of stability, sports specific demands, high volume or intensity of practice and competition, biomechanical deficits, and poor technique. Following injury, the return to competition process includes nonsurgical or surgical treatment, comprehensive rehabilitation, and a structured return to sports program. The return to sports continuum is divided into phases which include return to practice of the sport, return to competition at a lower level or with reduced performance, and return to expected performance. Components of the return to sports decision include clinical evaluation of physical and psychological readiness, measurement of muscle strength using isokinetic tests, evaluation of overhead functional tasks, and progression in a supervised interval throwing program. The evidence for the effectiveness of return to sports programs following shoulder injury is limited but evolving and is an area that will merit continued investigation.

Objective and subjective measures to guide upper extremity return to sport testing: A modified Delphi survey

OBJECTIVE

To identify which subjective and objective tests do content experts utilize to help guide return to sport (RTS) decision making for an athlete after an upper extremity (UE) injury?

METHODS

A modified Delphi survey was utilized, including content experts in UE rehabilitation. Survey items were identified based on a literature review identifying current best evidence and practice for UE RTS decision making. Content experts (n = 52) were identified, having a minimum of 10 years of experience with rehabilitation of UE athletic injuries, and 5 years of experience using an UE RTS algorithm to guide decision making.

RESULTS

Expert consensus was achieved on a combination of tests utilized within an UE RTS algorithm: 1. Tissue healing time frame is an important consideration in RTS decision making; 2. Patient reported outcome measures should be utilized specifically, DASH and NPRS 3. Strength is measured by handheld dynamometer and is an important consideration. 4. ROM should be utilized and is an important consideration. 5. Physical performance tests utilized include: Closed Kinetic Chain Upper Extremity Stability test, Seated shot-put test and lower extremity/core tests.

CONCLUSIONS

This survey reached expert consensus on which subjective and objective measures to utilize to evaluate RTS readiness after UE injury.

Shoulder muscle imbalance as a risk factor for shoulder injury in elite badminton players: A prospective study

OBJECTIVES

To assess the impact of preseason shoulder testing on the risk of significant shoulder injury (SSI) in elite badminton players.

DESIGN

Prospective cohort study.

SETTING

Secondary care, academic medical center.

PARTICIPANTS

Nineteen elite badminton players (19.37 ± 4.79 years, n = 13 males).

MAIN OUTCOME MEASURES

At preseason, they had shoulder examination tests including the table-to-acromion distance and the glenohumeral rotation range of motion. The glenohumeral internal rotation deficit (GIRD) was calculated. Isokinetic internal and external rotator shoulder muscle strength was tested at 60°/s (concentric and eccentric modes) and 240°/s (concentric mode). Bilateral strength ratio (non-dominant:dominant) and unilateral agonist:antagonist conventional and functional ratios (FR: eccentric-to-concentric) were calculated.

RESULTS

During the follow-up time of 38 weeks, SSIs were assessed by an experienced sport physician and 42% of the participants sustained at least one SSI at their dominant side. The preseason GIRD and FR at 240°/s (FR₂₄₀) were independently associated with SSIs (G² = 6.28, p = .012 and G² = 6.23, p = .013, respectively). FR₂₄₀ < 0.69 (odds ratio = 28.0) and GIRD> 14° (odds ratio = 36.14) were predictors for SSIs.

CONCLUSIONS

Lower functional deceleration ratio and greater GIRD are associated with a higher risk of SSI at the dominant side in elite badminton players.

Assessment of return to play after an acute shoulder injury: protocol for an explorative prospective observational German multicentre study

INTRODUCTION

To date, there is no valid single test or battery of tests for informing return-to-play (RTP) decisions following an acute shoulder injury. The purpose of this exploratory study is to evaluate a diagnostic test battery based on a Delphi consensus at the time of unrestricted return to team training after acute shoulder injury.

METHODS AND ANALYSIS

Data for this prospective multicentre cohort study are collected at two measurement time points: when the respective physician clears the patient for RTP (t1) and 12 months after RTP (t2). The study participants are 18-35 years old athletes participating at a professional level in the following team sports: handball, basketball, ice hockey, soccer, volleyball and American football. Maximum comparability will be ensured via uninjured matched pair teammates. To assess the subjective assessment of shoulder functioning and the athlete's readiness to RTP, patient-reported outcome measures (Western Ontario Shoulder Instability Index, Quick-Disabilities of the Arm, Shoulder and Hand, Psychological Readiness of Injured Athlete to Return to Sport and Shoulder Instability-Return to Sport after Injury) will be completed. After a medical check-up with a range of motion and anthropometric measurements as well as clinical tests, the participants will perform a structured warm-up protocol. The functional tests comprise handgrip strength, upper quarter Y-balance test, isometric strength, closed kinetic chain upper extremity stability test, wall hop test, functional throwing performance index and the unilateral seated shot put test and isokinetic tests.

ETHICS AND DISSEMINATION

The results of this study will be disseminated through peer-reviewed publications and scientific presentations at national and international conferences. Ethical approval was obtained through the Institutional Review Board of Martin-Luther-University Halle-Wittenberg (reference number: 2022-016).

TRIAL REGISTRATION NUMBER

DRKS00028265.

Shoulder Rotational Strength and Range of Motion in Unilateral and Bilateral Overhead Elite Athletes

CONTEXT

Overhead athletes place tremendous demands on the shoulder complex, which result in adaptive kinematics but potential susceptibility to injury. This study aimed to compare shoulder glenohumeral range of motion (ROM) and rotator muscles strength in bilateral and unilateral overhead sports.

DESIGN

Cross-sectional study; secondary care.

METHODS

Forty-two elite athletes (17.7 [4.5] y; 42.9% female), including 18 swimmers and 24 badminton players, were included. Preseason glenohumeral rotation ROM and isokinetic shoulder internal and external rotator muscles strength was tested (60°·s-1). Bilateral (nondominant:dominant) and agonist:antagonist (external rotator:internal rotator) conventional and functional deceleration ratios (eccentric to concentric) were calculated. The impact of sport and number of competitive years on shoulder ROM and strength was tested.

RESULTS

Badminton players had greater glenohumeral internal rotation deficit, total ROM deficit, and lower bilateral strength ratio than swimmers (P < .050). Rotational strength was positively associated with the competitive years, but greater in swimmers (P < .050) and on the internal rotator (P < .001). The functional deceleration ratio was negatively associated with the competitive years on the dominant side in swimmers and for both sides in badminton.

CONCLUSIONS

Unilateral overhead athletes had greater ROM and rotational strength asymmetries than bilateral athletes. Interestingly, the functional deceleration ratio was lower over time on the dominant shoulder for both sports, but, surprisingly, also on the nondominant shoulder in badminton, potentially creating a greater risk for shoulder injuries.

Shoulder rotation strength and overhead shooting speed associated with prior shoulder injury in water polo players

This study aimed to differentiate peak ball speed during shooting and shoulder rotation strength of the dominant arm between previously injured (PI) and uninjured (UI) water polo players. Nine PI and nine UI players performed 10 shots at 6 m from the goal mouth and three sets of three repetitions of isokinetic shoulder strength tests at 180 degrees/s on a dynamometer. Peak ball speed and shoulder concentric internal rotation (CIR) and eccentric external rotation (EER) peak torque (PT) and total work (TW) normalised to body mass were measured. EER:CIR PT and TW ratios were calculated. All PI versus UI comparisons were made using an Independent Samples T-Test. PI players shot 6% faster, produced 18% more CIR PT, and had lower EER:CIR PT (22%) and TW (34%) ratios compared with UI players. Shoulder TW compared with PT ratios could be more sensitive in differentiating PI versus UI players as TW takes into account the muscles' capacity throughout full active ROM. Practitioners could expand their foci to monitor shoulder EER:CIR TW ratios, in addition to PT ratios, to identify muscle imbalances in water polo athletes who might be at risk of injury/reinjury, and thereafter design interventions to reduce these imbalances.

Etiologic Factors of Rotator Cuff Disease in Elderly: Modifiable Factors in Addition to Known Demographic Factors

With the aging society, musculoskeletal degenerative diseases are becoming a burden on society, and rotator cuff disease is one of these degenerative diseases. The purpose of this study was to examine the incidence of shoulder osteoarthritis and the etiologic factors of rotator cuff disease in the Korean elderly population. A total of 102 patients performing ultrasonography were recruited, and their demographic factors were analyzed. As functional factors, visual analog scale and the peak torque of external and internal rotators of the shoulder using an isokinetic dynamometer were measured. As an anatomical factor, the acromiohumeral distance in the plain radiograph of the glenohumeral anterior-posterior view was used. There were more female patients (65.7%) than male patients (34.3%). The age range with the highest number of respondents was 50–59 years old. The mean visual analogue score was 4.09 (Min 1 to Max 9). Age and dominant hand side factors appear to be the crucial etiologic factors of the presence and severity of rotator cuff disease. The lower net value of the external rotator strength is weakly related to the presence of rotator cuff disease after adjusting for age, and this is the only modifiable factor in the study.

Team Approach: Treatment of Shoulder Instability in Athletes

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Shoulder instability is a complex problem with a high rate of recurrence in athletes. Treatment of a first-time subluxation or dislocation event is controversial and depends on patient-specific factors as well as the identified pathology.

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Athletic trainers and physical therapists are an integral part of the treatment team of an in-season athlete who has experienced a shoulder instability event. Through comprehensive physiological assessments, these providers can effectively suggest modifications to the patient's training regimen as well as an appropriate rehabilitation program.

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Surgical intervention for shoulder stabilization should use an individualized approach for technique and timing.

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A team-based approach is necessary to optimize the care of this high-demand, high-risk population.

Isokinetic force-power profile of the shoulder joint in males participating in CrossFit training and competing at different levels

Background

As participants who engage in CrossFit training and competition perform a large volume of high intensity overhead activities, injuries to the shoulder are one of the most common in this sport. Previous research in other sports has indicated that the isokinetic force power profile of the shoulder joint (IPSJ) rotator muscles may assist in the prediction of shoulder injury.

Aim

Therefore, the objective of this study was to determine the IPSJ in males engaged in CrossFit training at different competitive levels.

Methods

In a cross-sectional study design, participants (age, 24.1 ± 2.7 years) classified as ‘beginner’ (n = 6), ‘intermediate’ (n = 7) or ‘advanced’ (n = 9) provided informed consent to participate in this study. The IPSJ assessment involved rotational and diagonal movements, including internal and external shoulder rotator muscles, at both 180°.s⁻¹ and 300°.s⁻¹. The variables analysed were peak torque/body mass (%), mean power (W) and the external/internal peak torque/body mass ratio (%). A Kruskal–Wallis test was used to compare the IPSJ of the three groups, with Dunn’s test used for post-hoc analysis. The alpha level was set at p < 0.05.

Results

The IPSJ showed greater torque and power values in those who competed at the advanced level as compared to those at a lower competitive level (i.e. intermediate, beginner). This was observed mainly for the internal rotation and internal diagonal movements at both 180°.s⁻¹ and 300°.s⁻¹. However, such differences between competitive levels were, in general, absent for the external rotation and external diagonal movements. Moreover, the participants from the advanced competitive level exhibited an imbalance of peak torque between the muscles responsible for the external–internal rotational and external-internal diagonal movements of the shoulder (i.e. peak torque external/internal ratio <66%), particularly in the dominant shoulder.

Conclusion

These findings suggest greater development of the shoulder internal rotators and a higher probability of shoulder injury in CrossFit athletes at the advanced competitive level. Based on these results, participants engaged in CrossFit training and competition may wish to increase the volume of training for the shoulder external rotator muscles to complement the large increases in shoulder internal rotator strength that occur as a part of their regular training regimes.

Upper limb muscle strength and knee frontal plane projection angle asymmetries in female water-polo players

Water-polo players frequently perform overhead throws that could result in shoulder imbalances. For overhead throws, execution of the 'eggbeater kick' (cyclical movement of the legs) is required to lift the body out of the water. Although a symmetrical action, inter-limb differences in task execution could lead to knee frontal plane projection (FPPA) differences. The present study examined imbalances shoulder and knee FPPA in female players. Eighteen competitive female field players (24.1 ± 5.5 years, 1.68 ± 0.06 m, 72.9 ± 13.3 kg) had their shoulder strength assessed in a shot-mimicking position with a portable dynamometer, standing and seated (isolating the shoulder contribution). Anterior: posterior and shooting: non-shooting shoulder comparison were made. Additionally, players performed a drop jump. Knee FPPA was recorded from digitising and comparing the frames just before landing and at stance phase. During standing, players exhibited higher shooting: non-shooting asymmetry (p = 0.032) in the anterior contraction direction, while during seated the shooting shoulder anterior: posterior asymmetry was higher (p = 0.032). Interlimb knee FPPA asymmetry was higher in the stance phase (p = 0.02). Despite the overhead throwing and egg-beater demands impacting differently on each limb, considerable asymmetries do not develop, suggesting the overall training requirements (e.g. swimming, resistance training) were sufficient to maintain the asymmetry within desirable limits.

Shoulder Isokinetic Strength Balance Ratio in Overhead Athletes: A Cross-Sectional Study

BACKGROUND

Studies have grouped different overhead sports and evaluated together the isokinetic strength of shoulder internal (IR) and external (ER) rotator muscles. However, muscular adaptations could be a consequence of the specific sport, and some strength imbalance between these muscles may exist as a consequence of the muscular demand unique to the sport. Therefore, grouping different overhead sports together may not be adequate.

PURPOSE

To compare strength balance ratios between different overhead sports (volleyball, handball, swimming, judo, baseball, softball, functional movements performed at high-intensity interval training, and tennis) with a control athletic group (no overhead group).

STUDY DESIGN

Cross-sectional study.

METHODS

A total of 237 athletes were submitted to isokinetic shoulder strength tests. The isokinetic concentric and eccentric peak torque values of shoulder internal IR and external ER rotator muscles were measured. Conventional (CR) and functional strength ratios (FR) were calculated.

RESULTS

There were no significant differences between the sports for the CR in the male group. Female softball athletes (90.4±13.6%) had a significantly higher CR than judo (67.3±6.9%), volleyball (74.9±15.9%), and swimming athletes (70.3±8.7%). In the female group, judo athletes had lower FR values (0.76±0.19) than soccer athletes (1.31±0.35), volleyball athletes (1.24±0.27), functional movements performed at high intensity (1.10±0.1), and softball athletes (1.40±0.39). Female handball athletes also had a lower FR (0.99±0.25) than soccer athletes (1.31±0.35) and softball athletes (1.40±0.39). Male handball (0.90±0.23), tennis (0.86±0.30), and judo (0.68±0.22) athletes had lower FR values than soccer athletes (1.20±0.21) and volleyball athletes (1.25±0.28).

CONCLUSIONS

CR for males may be analyzed together, as there were no significant differences between them. However, for females, the CR for softball athletes should be analyzed individually. As there were several differences between the overhead sports according to the FRs, the authors suggest caution in grouping overhead athletes across multiple sports. These results could have important implications for the design of injury prevention and rehabilitation programs associated with the shoulder joint in overhead sports.

LEVEL OF EVIDENCE

3.

Shoulder Strength and Range of Motion in Healthy Collegiate Softball Players

CONTEXT

Shoulder range of motion (ROM) and strength are key injury evaluation components for overhead athletes. Most normative values are derived from male baseball players with limited information specific to female softball players.

OBJECTIVE

To determine between-limb differences in shoulder ROM and strength in healthy collegiate softball players.

DESIGN

Descriptive laboratory study.

SETTING

University research laboratory and collegiate athletic training room Participants: Twenty-three healthy collegiate softball players (age=19.9 ± 1.2y; height=170.5 ± 4.3cm; mass=78.4 ± 11.3kg).

INTERVENTIONS

Outcome measures included shoulder ROM (internal [IR] and external rotation [ER]), isometric strength (IR, ER, flexion, abduction [135 degrees], and horizontal abduction), and a measure of dynamic strength (Upper Quarter Y Balance Test [UQYBT]).

MAIN OUTCOME MEASURES

Paired sample t-tests were used to determine between limb differences for each outcome measure.

RESULTS

Participants had significantly more ER ROM (12° more) and significantly less IR ROM (12° less) on the dominant arm, relative to the non-dominant arm. There were no significant differences between limbs for any of the isometric strength measures or for the UQYBT reach directions.

CONCLUSIONS

While female collegiate softball players demonstrated typical changes in ER and IR ROM in the dominant arm, they demonstrated relatively symmetrical performance across strength measures, which contrasts with previous studies using male baseball players.

Evaluation of Shoulder and Knee Isokinetic Strength Profile Among Elite Adolescent Badminton Players

CONTEXT

Badminton continues to be a highly competitive sport where training is introduced at an early age and load has intensified. This exposes players to a greater risk of injuries, in particular when assessing related training outcomes such as strength, agonist-antagonist ratio, and bilateral deficit among adolescents where age- and sex-associated growth and development should be considered.

OBJECTIVE

To evaluate strength profile of the upper and lower limbs among adolescent elite Malaysian badminton players.

DESIGN

Cross-sectional study.

SETTING

Laboratory.

PARTICIPANTS

Forty-eight asymptomatic athletes (24 males and 24 females) were grouped into early and late adolescence (13-14 y old and 15-17 y old, respectively).

MAIN OUTCOME MEASURE(S)

Strength (absolute and normalized) of the external/internal rotators of the shoulder and flexor/extensor of the knee and strength derivatives, conventional strength ratio (CSR), dynamic control ratio (DCR), and bilateral deficits were measured.

RESULTS

Males showed greater strength in all strength indices (P < .05). The older group had greater strength compared to younger for most of the upper and lower limb indices (P < .05); these effects diminished when using normalized data. For females, there was no age group effect in the shoulder and knee strength. All players displayed lower shoulder and knee normative values for CSR and DCR. Dominant and non-dominant knee strength were comparable between sex and age groups.

CONCLUSIONS

For males, growth and maturation had a greater contribution to strength gained compared to training, whereas for females, growth, maturation, and training did not improve strength. The normalized data indicated that training did not improve all indices measured apart from external rotator strength in females. All players also displayed lower normative values of CSR and DCR. These results suggest that training in elite adolescent Malaysian badminton players lacks consideration of strength gain and injury risk factors.

Effects of Thrower's Ten exercises on upper extremity performance: A randomized controlled study

OBJECTIVES

The Thrower's Ten Exercise program is an exercise program especially designed to improve the strength, power and endurance of the shoulder complex. The aim of this study was to investigate the effects of the Thrower's Ten exercises on the upper extremity performance in healthy sedentary individuals.

METHODS

36 healthy sedentary individuals completed this study conducted with a randomized controlled design. The subjects were divided into 2 groups: exercise and control. The exercise group received a training of the Thrower's Ten exercises of 50-minute sessions 3 times a week for a duration of 8 weeks. Before and after the study, the subjects were tested for dynamic balance on the upper extremity with the Upper Limp Y balance test and for explosive power with the medicine ball throw test. Moreover, the strength of the shoulder internal and external rotator muscles was measured with an isokinetic dynamometer at a speed of 60°/second. The study was registered on the Clinical Trials website by the number NCT04162886.

RESULTS

A comparison between the groups showed significant differences in terms of dynamic balance and explosive power (P < .05), but not in terms of isokinetic muscle strength and body composition (P > .05). On the other hand, comparisons of the dynamic equilibrium, explosive power and isokinetic muscle strength parameters within the exercise group returned statistically different results (P < .05).

CONCLUSIONS

The Thrower's Ten exercises represent an effective method to improve the balance on the upper extremity, explosive power and isokinetic strength in healthy sedentary individuals.

Reduced shoulder strength and change in range of motion are risk factors for shoulder injury in water polo players

OBJECTIVE

To determine whether pre-season shoulder ROM and strength can be used to identify athletes at risk of future shoulder injury.

DESIGN

Prospective cohort.

SETTING

High performance sports institute.

PARTICIPANTS

76 sub-elite water polo players.

MAIN OUTCOME MEASURES

Mean pre-season shoulder internal (IR) and external rotation (ER) ROM and strength values compared by gender, dominance and prospective injury status.

RESULTS

14-dominant shoulder injuries were recorded. There was a significant difference (p = 0.05) in total ROM difference (TROM) between the prospectively injured and no injury groups (-17.2°(30.4);-0.8°(13.3)), and dominant side ER strength (11.7%(2.4) vs 14.5%(2.8), p = 0.03) and IR strength (16.5%(3.0) vs 21.6%(4.9) as a percentage body weight (PBW) were also significantly different (p ≤ 0.03). Separate significant associations were found between future episodes of shoulder injury and; dominant shoulder TROM difference of ≥7.5°(OR 3.6,95%CI 0.8-16.0), ER strength as a PBW≤12.5%(OR 5.2,95%CI 1.0-27.9), and IR strength as a PBW≤16.8%(OR 13.8,95%CI 2.2-88.0).

CONCLUSION

Pre-season dominant TROM difference, and reduced shoulder IR and ER strength relative to body weight were significant predictors for future shoulder injury. Although further investigation with a larger sample size is required, achieving optimal values on these measures may reduce future episodes of shoulder injury in water polo players.

The effect of deafness on the physical fitness parameters of elite athletes

The purpose of this study is to determine the health-related physical fitness parameters of athletes, who are deaf. The study group consisted of 137 deaf athletes (52 females and 85 males with a mean age of 23.99±6.56 years) who have participated in the 2017 Deaflympics games. The assessed parameters included the isokinetic muscle strength, core endurance, balance assessments, grip strength, and body composition. At the end of the study, the following results were obtained. Hamstring/quadriceps ratio was in the range of 53%–54%, which was within 50%–60% of the normal limit. Endurance of the anterior and posterior core muscles was low as compared to the normative data. The athletes’ balance was better with their eyes open than closed; and the grip strength was low as compared to the normative data in the literature. Also, the body fat percentage of deaf female athletes were similar to ones in healthy individuals with sedentary lifestyle, whereas male ones had slightly lower body fat mass percentage. These results can be used as the initial reference parameters to define the training program requirements of deaf athletes.

Patterns and Associations of Shoulder Motion, Strength, and Function in MARSOC Personnel Without History of Shoulder Injury

Introduction

Military personnel are at an increased risk of shoulder injuries due to training and deployment demands, however, there is a lack of information on the tactical athlete's upper extremity profile. Therefore, the purpose of this study was to examine shoulder musculoskeletal characteristics, including range of motion (ROM), strength, and function, and the relationships between these measures in Marine Corps Forces Special Operations Command (MARSOC) personnel without history of shoulder injury.

Materials and Methods

Participants included 195 full-duty male MARSOC personnel (age: 25.38 ± 2.85 yr; height: 1.79 ± 0.06 m, mass: 82.79 ± 7.88 kg) without history of shoulder injury. Measurements of ROM, strength, and function were obtained bilaterally. Shoulder internal rotation (IR) and external rotation (ER) ROM were summed to calculate total arc of motion (ARC). Shoulder IR and ER strength were assessed using an isokinetic dynamometer. Function was evaluated with an explosive push-up.

Results

MARSOC personnel present with significantly increased ER ROM, and decreased IR ROM and ARC in their dominant shoulder. They demonstrated greater IR strength and peak force during the explosive push-up on the dominant side but no bilateral differences in average or peak rate were found. Correlation analyses suggest a weak inverse relationship between strength and ARC (r = -0.15 to -0.24). Positive relationships between strength and function were identified except for dominant IR strength and push-up variables. Those with the greatest ARC demonstrated significantly weaker IR and ER strength compared to those with less motion.

Conclusions

MARSOC personnel demonstrate shoulder ROM and strength symmetry patterns similar to overhead athletes. Increased dominant shoulder strength does appear to translate to a bilateral functional performance, but overall performance may be limited by the weaker nondominant upper extremity. As ARC increases, IR and ER rotation strength decrease. Repetitive, increased loading of the dominant shoulder during functional movements and training may increase risk of chronic, overuse-type injuries, common to the military. Unilateral exercises and movement analysis should be incorporated to encourage proper development of bilateral shoulder strength, which may be particularly important in those with high ranges of ARC.

Isokinetic Characteristics of Amateur Boxer Athletes

Aim: The kinetic chain of the punch of boxers is characterized by the contribution of the shoulder; however, the isokinetic muscle strength of shoulder’s rotators muscles has not been well studied so far, especially with regards to performance. Therefore, the aim of the present study was (a) to profile the isokinetic muscle strength of rotators of the glenohumeral joint, bilateral (BL), unilateral (UL) and functional ratios in amateur boxers, and (b) to examine the variation of these muscle strength characteristics by performance level.

Methods: Forty male amateur Greek boxers from three division levels (elite, n = 22; second division, n = 11; and third division, n = 7), and 10 non-athletes (control group) were tested, using the isokinetic dynamometer Kin-Com^TM in the scapular seated position under standard conditions. We examined (i) peak torque (PT) of internal (IR) and external (ER) rotators during concentric (CON) and eccentric (ECC) contractions at low (60°/s), medium (120°/s), and high speed (180°/s), (ii) BL, (iii) UL, and (iv) functional ratios of dominant (D) and non-dominant (ND) limbs.

Results: Boxers were stronger than control group in IR and ER at all speeds, and D outscored ND limb (p < 0.05). Elite boxers were stronger than group B and C (p < 0.05); however, when peak torque was expressed in relative to body mass values, these differences were attenuated. The BL ratios for the men athletes were under 10% at 60 and 180°/s, the UL ratios were lower at 60 and higher at 180°/s and significant lower in the dominant limb at all speeds. The functional ratios of IR ECC / ER CON were higher between the control group at all speeds and the ER ECC/IR CON ratios were between 60 and 180°/s, and the two limbs with higher values at 180°/s.

Conclusion: Boxers had the strongest dominant limb and their BL ratios were normal at all speeds except of 120°/s ECC. The UL ratios of ECC at 120 and 180°/s of ND were normal, and at the other speeds abnormal due to high IR. In addition, the functional ratios may be related to the kinetic chain of the punch, which in turn correlates with the contribution of ER of both limbs.

A Systematic Summary of Systematic Reviews on the Topic of the Rotator Cuff

BACKGROUND

The number of systematic reviews and meta-analyses published on the rotator cuff (RC) has increased markedly.

PURPOSE

To quantify the number of systematic reviews and meta-analyses published on the RC and to provide a qualitative summary of the literature.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

A systematic search for all systematic reviews and meta-analyses pertaining to the RC published between January 2007 and September 2017 was performed with PubMed, MEDLINE, and the Cochrane Database of Systematic Reviews. Narrative reviews and non-English language articles were excluded.

RESULTS

A total of 1078 articles were found, of which 196 met the inclusion criteria. Included articles were summarized and divided into 15 topics: anatomy and function, histology and genetics, diagnosis, epidemiology, athletes, nonoperative versus operative treatment, surgical repair methods, concomitant conditions and surgical procedures, RC tears after total shoulder arthroplasty, biological augmentation, postoperative rehabilitation, outcomes and complications, patient-reported outcome measures, cost-effectiveness of RC repair, and quality of randomized controlled trials.

CONCLUSION

A qualitative summary of the systematic reviews and meta-analyses published on the RC can provide surgeons with a single source of the most current literature.

Profiling the Isokinetic Muscle Strength of Athletes Involved in Sports Characterized by Constantly Varied Functional Movements Performed at High Intensity: A Cross-Sectional Study

BACKGROUND

Constantly varied functional movements performed at high intensity (FMHI) is a type of strength and general conditioning program that has gained widespread popularity in recent years. The very intense exercises performed with lower and upper limbs may create muscular asymmetry or imbalance between agonist and antagonist muscles, and therefore the characterization of isokinetic muscle strength, side-to-side difference, and balance ratios for lower and upper limbs may contribute to a better understanding of the modality characteristics.

OBJECTIVE

To evaluate the knee and shoulder strength of FMHI athletes of both sexes.

DESIGN

Cross-sectional study.

SETTING

Exercise physiology laboratory.

PARTICIPANTS

Sixty FMHI athletes (30 M/30 W) with more than 2 years' experience.

METHODS

Athletes performed isokinetic tests in both lower and upper limbs: concentrically at 60°/s and 240°/s and eccentrically at 240°/s.

MAIN OUTCOME MEASUREMENTS

Isokinetic peak torque of knee flexor and extensor and shoulder internal and external rotator muscles. Conventional and functional strength balance ratios and side-to-side strength difference.

RESULTS

Concentric peak torque values relative to total body mass for shoulder and knee joints were higher in men than women on both sides. Eccentric peak torque values for knee flexor-dominant and extensor-nondominant limbs showed no difference between the sexes. The knee conventional strength balance ratio for dominant and nondominant sides in women (51.5% ± 7.0% and 51.0% ± 7.1%, respectively) and for dominant and nondominant sides in men (54.4% ± 15.2% and 51.5% ± 9.9%, respectively) were no different between the sexes or limbs. The shoulder conventional strength balance ratio was higher in women (78.1 ± 13.2%) than in men (67.6% ± 10.9%) on the nondominant side. Knee and shoulder functional strength balance ratios in nondominant limbs were higher for women than men. Both sexes presented no side-to-side difference for knee joints or muscles, or for shoulder IR muscles, but ER was stronger in dominant limbs.

CONCLUSIONS

These data from highly trained FMHI athletes can be compared to that of other athletes to help determine individual weaknesses, strengths, and imbalances, and may be useful for designing training programs.

LEVEL OF EVIDENCE

III.

Are there bilateral isokinetic shoulder rotator differences in basketball male players?

BACKGROUND

The internal (IR) and external (ER) rotator shoulder strength are often assess in the upper limb sports to prevent a risk of injuries. The purpose of this comparative study was to measure the agonist/antagonist balance of shoulder strength and to determine whether significant differences exist between the dominant and nondominant sides in basketball players compared to a control groups.

METHODS

During the championship, 23 elite male-basketball players (BB) and 23 healthy males (CG) were tested bilaterally on a Cybex Norm isokinetic dynamometer in a seated position with 45° shoulder abduction in the scapular plane at 60°.s-1 and 180°.s-1 in concentric (CON) and 60°.s-1 in eccentric (ECC) modes.

RESULTS

No significant differences were found for normalized values to body weight (N.m/kg-1) between the both groups and ER/IR, ECC/CON and functional deceleration ratios were similar. BB have a bilateral difference with higher ER of the dominant side comparatively to the opposite (P<0.05).

CONCLUSIONS

Unlike other sports that increase the performance of IR dominant side, the basketball player isokinetic profile could indicate a strengthening in the external rotators of the dominant side. This bilateral difference could be explained by the repetition of the specific movements in the ball control but this was not large enough for the ER/IR ratios to be significantly different with CG. The ratios analysis does not report an imbalance associated with a high risk of shoulder injuries.